In the sintering of YIG, abnormal grain growth phenomena were observed. This abnormal grain growth is related to the sintering temperature in this experiment. In the sintering below 1450$^{circ}C$, the sintered body showed narrow size distribution. However, in the sintering at 1450$^{circ}C$, a few grains grew rapidly with respect to other grains, and bimodal size distribution was appeared. From the observation of the microstructure, liquid phase was not observed far from the abnormally grown large grains, but only near the large grains. This means that the abnormal grain growth was caused by the nonuniform distribution of liquid phase which promote the grains growth. Because the growth rate of grains near the liquid phase is much higher than that of the other grains, a few grains grow rapidly. This nonuniform distribution of liquid phase was thought to be due to the nonuniform mixing of the calcined powders. This abnormal grain growth was suppressed by enhancement of the compositional uniformity by multiple calcination.